@thi.ng/shader-ast-stdlib/math/additive.js

Function collection for modular GPGPU / shader programming with @thi.ng/shader-ast

import { F } from "@thi.ng/shader-ast/api/types";
import { forLoop } from "@thi.ng/shader-ast/ast/controlflow";
import { defn, ret } from "@thi.ng/shader-ast/ast/function";
import { gensym } from "@thi.ng/shader-ast/ast/idgen";
import { FLOAT0, FLOAT05, float } from "@thi.ng/shader-ast/ast/lit";
import {
  add,
  addSelf,
  inc,
  lt,
  mul,
  mulSelf
} from "@thi.ng/shader-ast/ast/ops";
import { sym } from "@thi.ng/shader-ast/ast/sym";
const additive = (type, fn, oct = 4, name = gensym("additive_")) => defn(F, name, [[type], [type], F], (pos, shift, decay) => {
  let n;
  let amp;
  return [
    n = sym(FLOAT0),
    amp = sym(FLOAT05),
    forLoop(
      sym(FLOAT0),
      (i) => lt(i, float(oct)),
      inc,
      (i) => [
        addSelf(
          n,
          mul(amp, fn(add(pos, mul(i, shift))))
        ),
        mulSelf(amp, decay),
        mulSelf(pos, 2)
      ]
    ),
    ret(n)
  ];
});
export {
  additive
};